Apparatus for burning powdered fuel.



H. R. BARNHURST.

APPARATUS EUR BURNING PUWUURUD FUEL.

APPLICATION FILED 11111.21, 1910.

961,671 Patented June 14,1910.

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WITNESSESQ; mvENTUU z M /MW @M25/M ATTORNEY :Nmiw i' :3s/wm co.Fnom-mnoGnAPNERs. wasnammm. 04 t;

HENRY R. BARNI-IURST, OF ALLENTOWN,

ENNSYLVANIA, ASSIGNOR 0F ONE-HALF T0 HENRY GREGORY BARNI-IURST, 0FCATASAUQUA, PENNSYLVANIA.

APPARATUS FOR BURNING PIJ'DERED FUEL.

To all whom it' may concern.'

Be it known that I, HENRY It. BAnNr-IURST, a citizen of the UnitedStates, residing at Allentown, county of Lehigh, State of Pennsylvania,have invented certain new and useful Improvements in Apparatus forBurning Powdered Fuel; and I. do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

In an application for Letters Patentof the United States, filed of evendate herewith, I have described a method of effecting the combustion,for industrial purposes, of fuel of such a character that ordinaryexpediente for burning it are attended with but indiiferent results. @neof the materials for whose combustion the method referred to isparticularly intended is anthracite culin, reduced, by mechanical means,to a fine powder. This line powder, ground for example to such a degreeof subdivision that S5 per cent. of it will pass through a screen of No.200 mesh, is not self-ignitible when mixed, in the ordinary way, with acarrying body of air and projected into a combustion chamber in theusual manner familiar to the art of burning' pulver-ized fuel. In thisrespect, the finely divided anthracite culrn is similar to many otherdifcultly ignitible fuels and waste materials, such as low gradebituminous dusts of difiicult ignit-ibility, containing high percentagesof ash, tank mud from coal washeries, coke breeze and charcoal breeze,wherein the amount of volatile hydrocarbon present is not sufficient ofitself to sustain free ignition when reduced to a like line powder.

By the practice of the method set forth in my companion application I amenabled to effect the combustion of these difficultly ignitible fuels,by establishing and maintaining appropriate conditions in the combustionchamber. To this end I first bring the combustion chamber to such aheat, by the combustion therein of fuel appropriate to the purpose, thatupon the subsequent admission of the body of air and anthracite culm orits equivalent, ignition thereof will take place, and I continuouslymaintain this ignition and the effective combustion of the otherwisenon-ignitible mixture by conducting the incoming current in closeproximity to a highly heated inner surface of the coni- Specfioation ofLetters Patent.

Application iled January 21, 1810.

Patented June 14, 1910.

Serial No, 539,401.

bustion chamber (as, for instance, the arch thereof) and maintain thisinner surface at the ignition point as againstthe cooling e'ect of theincoming mixture by the expedient of conveying' the products ofcombustion after they leave the combustion chamber into a. flueextending' along the reverse side of the ignition wall or arch, which ismade sufficiently thin to readily transmit from the passing products ofcombustion an amount of heat suiiicient for the purpose. The heat thustransmitted to the incoming current of air and difhcultly ignitible fuelis supplemented by heat radiated directly thereto from a return currentof the products of combustion within the combustion chamber itself, thisreturn current forming with the incoming current a return bend or loopand preferably making its exit at or near the point at which theinjecting devices for the fuel enter the combustion chamber. Thisparticular location of the injector devices also permits them to beexposed to the heat of the outgoing products of combustion and likewisecauses a minor portion of the products of combustion to be entrainedwith the entering mixturer thereby adding their sensible heat thereto.

The present application relates to apparatus for carrying the methodinto effect, the accompanying drawing' illustrating the form which Iprefer and have found to operate well in practice.

In the drawing, Figure l represents a-longitudinal sectional view of mysaid preferred form of apparatus; Fig. 2 represents a cross sectionalview thereof taken on a plane indicated by the line 2 0 of Fig. 1.

Similar letters of reference indicate similar parts in both views.

Referring to the drawing, A indicates the front outer wall of thefurnace structure, B the outer side walls thereof, and C the combustionchamber. One of the walls of the combustion chamber (preferably the archa thereof) is made quite thin, say nine inches in thickness orthereabout, and of refractory material conducive to heat, (the moreconducive, the better) and is intended to serve as the ignition wall orarch hereinbefore referred to. Accordingly, the pipe o through which themixture of air and pulverized culm or other difficultly-ignitible fuelis projected, and the surrounding conduit or twyer c through which anadditional amount of atmospheric air is drawn in, are located just outof line with the .inner surface of the wall or arch a, so as to directthe incoming fuel cloud along and in close proximity thereto.

At its furthermost or rear end, the combustion chamber C is curved, asshown, and its walls are preferably made smooth throughout so as tominimize the product-ion of interfering eddy currents. The exit port clfor the products of combustion is located in proximity to the entranceconduit for the fuel cloud, and the said exit port leads into a wide andlarge Hue e on the reverse or upper side of the wall or arch a. In thisflue of large dimensions, the products of combustion are slowed down toa velocity of say 20 to 22 feet per second, and have the opportunity toimpart a suflicient portion of.

their heat to the wall or arch a and therethrough to the entering fuelcloud to raise the temperature of the latter and thus to assist incontinuously maintaining it at the full i nition point.

Be ore injecting into the combustion chamber the mixture of air andpulverized culm or the like, I heat the combustion chamber to such adegree and in such manner as will. bring it to the temperature necessaryto initiate the ignition and combus- -tion of the otherwisenon-ignitible mixture.

While this preliminary heating of the combustion chamber may be effectedin various ways, such as by building therein a wood fire, I nd that itmay be quickly and conveniently brought to a high temperature byintroducing through the pipe b, after the wood fire has been burning fora time, the

' usual mixture of air and finely pulverized ordinary bituminous coal,which then readily ignites because of the large proportion of richhydrocarbons present in that fuel.

As soon as the combustion chamber has been sufficiently heated, andparticularly as soon as the inner surface of the wall or arch a has beenraised to the temperature necessary for insuring and maintainingignition ofthe mixture of air and dificultlyignitible fuel, the supplyof pulverized bituminous coal is cut off and the pulverizeddiificultly-ignitible fuel is substituted therefor. The regularoperation then proceeds continuously. The mixture of air and pulverizeddiilicultly-ignitible fuel projected into the combustion chamber throughthe pipe 5 draws in an additional supply of air through the conduit cand is at once ignited by the heat radiated upon it from the ignitionwall or arch a. The ignited fuel cloud traveling rapidly along the wallor arch a constitutes the entrance branch of the loop. The ignitionprogresses from the periphery toward the center of the fuel cloud, andincreasing in volume as it advances, it is finally deflected by thecurved or lleted rear wall of the combustion chamber and merges into thereturn branch of the loop, which takes its way toward the exit port el,in the form of a flame cloud burning ercely by the time it reaches thefront part of the combustion chamber. The heat of the flame cloudconstituting the return bend of the loop is thus radiated, as theoperation proceeds, upon the entering branch of the loop consist-ing ofthe continuously supplied and ignited fuel cloud. A portion of t-heproducts of combustion from the llame cloud is drawn into the enteringfuel cloud at the point where the latter issues from the inj ector intothe combustion chamber, thereby imparting to the fuel cloud the sensibleheat of the portion of the products of combustion thus ent-rained.Coincidentwith the intense inflaming of the return bend or current ofthe loop, the accompanying air and products of combustion haveexperienced an enormous expansion, so that the flame cloud rises throughthe uptake in strong volume and with a velocity which is greatest at themiddle of the arch a. Accordingly, I have selected this point as thepreferable point of location for the fuel injector, although it will beunderstood that I do not limit myself to such location, as in someinstances, especially, for large furnaces, it may be found desirable touse more than one fuel injector. Finally, the main body portion of theproducts of combustion, issuing and passing along the wide and spaciousflue e on the reverse side of the highly conducting thin wall or arch akeeps said wall or arch continuously at the high temperature necessaryfor the maintenance of ignition of the entering cloud of air andpulverized diflicultly-ignitible fuel. After subserving' the functionsdescribed, the products of combustion pass on to place of use for whichthey are intended, as, for instance, a steam boiler, a kiln, thelaboratory of a metallurgical or heating furnace, or the like.

IVhile I have described in particular the specific application of myapparatus to the combustion of the waste material known as anthraciteculm, yet it will be quite evident that the apparatus described isequally applicable to other fuels of dificult ignitibility, which areusually, for this very reason, regarded as waste fuels, and exist atpresent, in enormous quantities. Such materials form at the present timea large item in the waste of our natural resources, and their eHicientutilization is of great economic and national importance. Among suchmaterials I would enumerate coke breeze, charcoal breeze, tank mud fromcoal washeries, and low grade bituminous dusts of difficultignitibility, containing high percentages of ash. Furthermore, it isquite Within the range of practicability to pulverize the smaller sizesof anthracite coal and burn them as dust by my invention.

I-Iaving thus described my invention, what I claim is l. Apparatus forburning powdered fuel, consisting of a combustion chambei having' anexit fine for the passage of the products of combustion on leaving thecombustion chamber, and having a wall common to the combustion chamberand said exit flue, said wall being sufficiently thin to transmittherethrough to the point of discharge of the fuel, along the innersurface of the wall, the amount of heat necessary to maintain ignitionthereat, and means for projecting into the combustion chamber and alongthe inner surface of said wall a body of air mixed with fuel;substantially as described.

2. Apparatus for burning powdered fuel, consisting of a combustionchamber having an exitflue for the passage of the products of combustionon leaving the combustion chamber, and having a wall common to thecombustion chamber and said exit flue, said wall being` sufficientlythin to transmit therethrough to the point of discharge of the fuel,along the inner surface of the wall, the amount of heat necessary tomaintain ignition thereat, and an injector for projecting into t-hecombustion chamber along the inner surface of said wall, a body of airmixed with fuel powder, said injector being located in proximity to theport leading from the combustion chamber into the exit flue for theproducts of combustion, whereby the mixture of air and fuel and productsof combustion thereof will traverse the combustion chamber in the formof a loop; substantially as described.

3. Apparatus for burning powdered fuel, consist-ing of a combustionchamber having an exit flue for the passage of the products ofcombustion on leaving' the combustion chamber, and having a wall commonto the combustion chamber and said exit flue, said wall beingsufficiently thin to transmit therethrough to the point of discharge ofthe fuel, along the inner surface of the wall, the amount of heatnecessary to maintain ignition thereat, and an injector for injectinginto the combustion chamber along the inner surface of said wall a bodyof air mixed l with fuel powder, said injector being located 1 inproximity to the port leading from the combustion chamber into the exitflue for the products of combustion, and extending across said portso asto lie in the path of the outgoing products of combustion, whereby themixture of air and fuel, and products of combustion thereof, willtraverse the combustion chamber in the form of a loop, and whereby theincoming body of air and fuel will be preheated by heat from theproducts of combustion and a portion of the products of combustion willbe entrained with the said entering mixture; substantially as described.et. Apparatus for burning powdered fuel, comprising a combustion chamberprovided at its top with a thin arch constituting one of the walls ofsaid chamber, a second arch above the first and forming therewith a wideand spacious flue into which the products of combustion enter from thecombustion chamber, and an injector for injecting' into the combust-ionchamber along the inner surface of the thin arch from front to rearthereof a body of air mixed with powdered fuel, said injector beinglocated in proximity to the port leading' from the combustion chamberinto said exit flue for the products of combustion; substantially asdescribed.

5. Apparatus for burning powdered fuel, comprising a combustion chamberprovided at its top with a thin arch constituting one of the walls ofsaid chamber, a second arch above the first and forming therewith a wideand spacious flue into which the products of combustion enter from thecombustion chamber, and an injector for injecting into the combustionchamber along the inner surface of the thin arch from front to rearthereof a body of air mixed with powdered fuel, said injector being'located in proximity to the port leading from the combustion chamberinto said exit fine for the products of combustion, and extending acrosssaid port so as to lie in the path of the outgoing products ofcombustion; substantially as described.

In testimony whereof I aflix my signature, in presence of two witnesses.

HENRY R. BARNI-IURST.

Witnesses SHIRLEY I-I. KING, RAYMOND W. LnN'rz.

